1. Field of the Invention
Edwardsiella ictaluri, the causative agent of enteric septicaemia of catfish (ESC), has become widely spread throughout the catfish industry since its original isolation in 1977 [Hawke, J. Fish. Res. Board Canada 36:1508-1512 (1979); Hawke et al., Int. J. Syst. Bacteriol. 31: 396-400 (1981)]. This pathogen has been isolated from cultured channel catfish in most areas of the United States where this species is cultured and from walking catfish in Thailand [Kasornchandra et al., J. Fish Dis. 10: 137--138 (1987)]; therefore, it is likely that this organism has a wide geographical range.
This invention relates to hybridoma cell lines which produce monoclonal antibodies (Mabs) having reactivity specifically toward an E. ictaluri antigen of a molecular weight of about 14,000, 39,000, 48,000, 60,000, 66,000, 83,000, and 93,000 daltons. The Mabs are useful for diagnosis of E. ictaluri in body fluids and tissues of catfish and are promising reagents for identification and purification of the aforementioned antigens from E. ictaluri. The purified antigens will be useful in diagnosis and vaccination of E. ictaluri.
2. Description of the Prior Art
Recently, Plumb et al. [J. Fish Dis. 11: 499-509 (1988)] reported the use of channel catfish anti-E. ictaluri serum to identify distinct antigens of E. ictaluri. The catfish antibodies were reported to be reactive with antigens of approximately 34,000 and 60,000 daltons and were believed to be dominant immunoproteins or immunodominant antigens of E. ictaluri.
E. ictaluri is reported to be used as whole cells in an enzyme-linked immunoabsorbent assay (ELISA) to detect E. ictaluri antibodies in infected catfish [Waterstrat et al., J. Fish Dis. 12: 87-95 (1989)]. No evidence was presented for E. ictaluri specificity by ELISA using whole cells as antigen.